Electronic devices, such as cell phones, personal digital assistants (PDAs), smart phones, communication devices, computing devices (e.g., desktop computers and laptops) often have microphones to detect, receive, record, and/or process sound. For example, a cell phone/smart phone may use a microphone to detect the voice of a user for a voice call. In another example, a PDA may have a microphone to allow a user to dictate notes or leave reminder messages. The microphones on the electronic devices may also detect noise, in addition to detecting the desired sound. For example, the microphone on a communication device may detect a user's voice (e.g., desired sound) and background noise (e.g., ambient noise, wind noise, other conversations, traffic noise, etc.).
One method of reducing such background noise is to use two microphones to detect the desired sound. A first microphone is positioned closer to the desired sound source (e.g., closer to a user's mouth). The first microphone is designated as the primary microphone and is generally used to detect the desired sound (e.g., the user's voice). A second microphone is positioned farther away from the desired sound source than the first microphone. The second microphone is designated as a secondary microphone and is generally used to detect the background (e.g., ambient) noise. The second microphone may also detect the desired sound as well, but the intensity (e.g., the volume) of the desired sound detected by the second microphone will generally be lower than the intensity of the desired sound detected by the first microphone. By subtracting the signals (e.g., the sound) received by the second microphone from the signals (e.g., the sound) received from the first microphone, a communication device may use the two microphones to reduce and/or cancel the background noise detected by the two microphones.
Generally, when two microphones are used to reduce the background noise, the microphone designations or assignments are permanent. For example, if the second microphone is designated the primary microphone and the first microphone is designated the secondary microphone, these assignments generally will not change.